package main

import "fmt"

/*
In a deck of cards, each card has an integer written on it.
Return true if and only if you can choose X >= 2 such that it is possible to split the entire deck into 1 or more groups of cards, where:
Each group has exactly X cards.
All the cards in each group have the same integer.

Example 1:
Input: deck = [1,2,3,4,4,3,2,1]
Output: true
Explanation: Possible partition [1,1],[2,2],[3,3],[4,4].

Example 2:
Input: deck = [1,1,1,2,2,2,3,3]
Output: false´
Explanation: No possible partition.

Example 3:
Input: deck = [1]
Output: false
Explanation: No possible partition.

Example 4:
Input: deck = [1,1]
Output: true
Explanation: Possible partition [1,1].

Example 5:
Input: deck = [1,1,2,2,2,2]
Output: true
Explanation: Possible partition [1,1],[2,2],[2,2].

Constraints:
1 <= deck.length <= 10^4
0 <= deck[i] < 10^4
*/

func main() {
	fmt.Println(hasGroupsSizeX([]int{1, 2, 3, 4, 4, 3, 2, 1}))
	fmt.Println(hasGroupsSizeX([]int{1, 1, 1, 2, 2, 2, 3, 3}))
	fmt.Println(hasGroupsSizeX([]int{1, 1, 1, 2, 2, 2, 3, 3, 3}))
	fmt.Println(hasGroupsSizeX([]int{1}))
	fmt.Println(hasGroupsSizeX([]int{1, 1}))
	fmt.Println(hasGroupsSizeX([]int{1, 1, 2, 2, 2, 2}))
}

func hasGroupsSizeX(deck []int) bool {
	deckM := make(map[int]int, len(deck))

	for _, v := range deck {
		deckM[v]++
	}

	gcdV := 0
	for _, v := range deckM {
		if gcdV == 0 {
			gcdV = v
		} else {
			gcdV = gcd(gcdV, v)
		}
	}

	return gcdV >= 2
}

func gcd(a, b int) int {
	if a%b == 0 {
		return b
	}

	return gcd(b, a%b)
}
